Recently, with the spread of multilayer wirings on a surface of semiconductor substrate, a so-called chemical mechanical polishing (CMP) technique, by which a semiconductor substrate is mechanically polished and planarized, has been used in producing devices.
In particular, accompanied to the tendency to a highly integrated LSI in recent years, a wiring used has been changed from conventional aluminum to copper (Cu) which has a lower electric resistance, and thus the CMP technique (Cu-CMP) has become essential, when semiconductors having a multilayer structure, in which copper wirings are provided in many layers on the surface thereof, are produced.
The CMP is a method for planarizing a surface of semiconductor substrate using a slurry containing abrasive grains such as silica, aluminum and ceria, and an object to be polished is silicon oxide films, wirings, plugs, or the like.
And the semiconductor surface after the CMP process is contaminated with a large amount of abrasive grain itself used, metals contained in the slurry, or metallic impurities derived from metallic wirings or metallic plug polished, and further various kinds of particles.
Contamination of the surface of semiconductor substrate with the metallic impurities or the particles affects electric characteristics of the semiconductor, and causes to lose reliability of devices. Further, since device is destructed when metallic contamination is significant, it is necessary to introduce a post-CMP cleaning process to remove metallic impurities or particles from the surface of semiconductor substrate.
Heretofore, various kinds of cleaning agents have been developed for use in various types of cleaning processes such as a cleaning process following the CMP process, and provided for use.
On the other hand, since metallic copper on a surface of semiconductor is highly active, and easily corroded by a slight oxidizing power, it tends to cause an increase of wiring resistance or wire breaking. Therefore, it is known that corrosion of metallic copper on a surface of semiconductor can be prevented by adding various kinds of metal corrosion inhibitors [for example, an aromatic type compound represented by benzotriazole(BTA)s and imidazoles, a cyclic compound such as mercaptoimidazole and mercaptothiazole, an aliphatic alcohol type compound which has a mercapto group in a molecule and a carbon to which said mercapto group is bonded and a carbon to which a hydroxyl group is bonded links adjacently such as mercaptoethanol and mercaptoglycerol]. In particular, in a slurry used in the above-described Cu-CMP process, an inhibitor for metal corrosion as described above is added to prevent the polished metal surface from corrosion.
The metal corrosion inhibitor is supposed to be adsorbed on a surface of metal (for example, Cu) of semiconductor surface and form a metal corrosion inhibiting film (for example, a metal corrosion inhibitor—Cu film such as a Cu-BTA film), and thus to prevent corrosion of the metal (for example, Cu).
However, these metal corrosion inhibitors may remain on a surface of semiconductor as a so-called carbon defect.
There has been a problem that when a semiconductor having a carbon defect remaining on a surface thereof is subjected to heat treatment in the subsequent process, during working of a device or the like, the carbon defect is burnt to oxidize a wiring material resulting in deterioration of the device performance, or an apprehension that multilayer wiring executed without removing the carbon defect tends to put the flatness of upper layer part into disorder, and make a correct lamination difficult to cause a serious defect in working of the device.
However, a cleaning agent, which is conventionally used in various cleaning processes such as a post-CMP cleaning process, cannot sufficiently remove the carbon defect, or apt to remove a metal corrosion inhibiting film that is needed to prevent corrosion of metal surface as described above. Thus, an effective means has not been found which can remove only the carbon defect while maintaining the metal corrosion inhibiting effect, without removing a metal corrosion inhibitor—Cu film, in particular, a Cu-BTA film as described above.    Patent Reference 1:JP-A-4-130100 (Claims 1 to 3)Patent Reference 2:    JP-A-7-79061 (Claim 1)Patent Reference 3:    JP-A-10-72594    Patent Reference 4:JP-A-10-26832 (Claims 1 to 15)    Patent Reference 5:JP-A-11-316464 (Claims 1 to 6)    Patent Reference 6:JP-A-2002-20787 (Claims 1 to 36)    Patent Reference 7:JP-A-2003-13266 (Claims 1 to 42)